The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

You’ve left me GOB smacked,
the cops using cutting-edge technology,
Money Heist Season 1, Episode 10

and because it's a special day,
a chewable GOB of tree sap.
The Big Bang Theory Season 11, Episode 11